This application relates to memory addressing and, more particularly, to performing console redirection where memory accesses are redirected.
A processor-based system connected to a computer network may communicate with other entities on the network. Because of the proliferation of networks, a computer in an office down the hall, a server in another city, or an e-mail recipient in another country may be accessible to the processor-based system.
Managing a network of computers typically involves sophisticated software and highly trained individuals. Further, because some entities on the network may physically be remote to a central site, remote management of network entities is increasingly featured in network management software.
Console redirection is one scheme for addressing remote management. Console redirection allows a user, such as a network administrator, to both control and retrieve status information about a system that physically resides in a location remote to the user, e.g. a managed system. For example, during console redirection, keystrokes entered on a user computer system may be received by the managed system. In this manner, the remote key entry operates as if the keys had been entered on the keyboard of the managed system. Software running on the user system, the managed system, or both, may likewise cause data intended for the managed system to be redirected to the user computer system, such as to a display. The user system may thus interact and observe operation of the managed system. Console redirection may be performed over a number of physical media, including a standard telephone line, a local-area network (LAN) line, a wide-area network (WAN) line, wireless media, and so on.
Often, processor-based systems may be configured as xe2x80x9cheadless.xe2x80x9d In headless systems, no keyboard or video monitor is connected to the system. Thus, the system may only be accessed from a remote terminal. Headless systems, such as servers, may be preferred by Internet service providers (ISPs), for example, because more servers may be packed into a given space.
In one implementation of console redirection, software periodically scans the video buffer of the managed system for activity. Where changes to the video buffer of the managed system are identified, the updates are sent, or redirected, to the video buffer of the user computer system. For headless systems, this method of console redirection works because the video buffer, although not the video display, remains present in the headless system.
Because the video display is not used in the headless system, it would be highly desirable to remove the associated video hardware as well. For example, a video subsystem may typically include a video graphics adapter (VGA) controller, input/output (I/O) registers, and a portion of memory to be used as the video buffer. In addition to providing cost savings, removing VGA hardware further enables other cards to be added to the headless system in place of the video controller. However, without a video buffer, the aforementioned console redirection scheme would not be implemented.
Thus, there is a continuing need to redirect memory accesses where no video buffer is available and to provide console redirection for such systems.